Fig. 1: Enterovirus inactivation by serine proteases is both virus type and protease specific.

Virus decay (Log₁₀ C/C₀) of (a) CVA9 or (b) CVB5 and E11 after an exposure to serine proteases. Each virus has been exposed to 20 μg/mL of Subtilisin A (n = 4) or BPT (n = 1) for 2 or 6 h. Infectivity experiments have been performed on BGMK cells and cytopathic effects (CPEs) measurements have been done 4-days post-infection. c Visualization of the CVA9 C-terminal end VP1 segment (strain Griggs, 1d4m), carrying a RGD motif. Modeling of CVA9 VP1 anchoring the C-terminal end of the protein has been performed using Modeller. d Screening procedure used to demonstrate the RGD-independent viral decay of CVA9 by serine proteases. PDB structures used for CVA9 (1d4m) and protease (1scn) visuals. e Comparison of CVA9 viral titers 5-days post-infection on BGMK and RD cells (t = 0.1667, p value: 0.8695 (ns); two-tailed unpaired t-test, n = 10). Comparison of CVA9 viral decay measured on BGMK and RD cells after an exposure either with 20 ug/mL BPT (f) (t = 3.583, p value: 0.0256 (*); two-tailed unpaired t-test, n = 3) or Subtilisin A (g) (t = 4.614, p value: 0.0005 (***); two-tailed unpaired t-test, n = 12) for 2 h. For each experiment involving a treatment with proteases, the LoD of the assay was 5-log₁₀. For all negative control experiments of inactivation (C₀), PBS has been used to replace serine proteases. e–g For each box plot, the horizontal bar within the interquartile range corresponds to the median of values. The vertical bar of each dataset corresponds to the distribution of minimum and maximum values.